We seek to extensively advance the technology for measuring health-related quality of life (HRQOL) in chronic kidney disease (CKD) using item response theory (IRT) and computerized adaptive testing (CAT) methods. HRQOL, accepted in clinical research as an important outcome, is a valuable predictor in CKD. Clinicians' intuitive assessment and monitoring of HRQOL influences treatment choices in CKD that enhance patient-caregiver communication in dialysis care. Respondent burden renders HRQOL measures impractical for widespread use in CKD. Short-forms have proven more practical and acceptable to patients; however, "ceiling" and "floor" effects result from measuring a limited range within each health domain. Lack of precision necessary to interpret individual patient scores is another major weakness of short forms like the SF-36. To address these deficiencies, Phase I activities will: (1) apply IRT to calibrate items administered at baseline in the NIDDK Hemodialysis Study (HEMO); (2) program CAT to simulate dynamic assessments that match questions to each patient's functional level (CKD.CAT); (3) estimate reductions in respondent burden, range of levels measured and score accuracy using CKD-CAT in comparison with the HEMO survey from existing data; and (4) evaluate the acceptance of actual CAT administrations relative to the original HEMO survey in a dialysis unit. The product of Phase I will be a prototype CKD-CAT with preliminary evidence regarding feasibility, acceptability and performance. In Phase II, items from the HEMO and Choices for Healthy Outcomes in Caring for End-Stage Renal Disease instruments will be calibrated on a common metric for each HRQOL domain to specifically address peritoneal dialysis. CKD-CAT will be evaluated (reliability, validity and precision) to create a fully operational system that facilitates clinical research and improves measurement in CKD clinical practice. By greatly lowering data collection costs, reducing respondent burden, eliminating "ceiling" and "floor" effects and increasing the precision of individual patient scores, routine monitoring of HRQOL may become feasible as a clinical tool in CKD, leading to acceptance of CAT for other chronic illnesses.